SPECTROPOLARIMETRIC EVIDENCE FOR A BIPOLAR FLOW IN BETA-LYRAE

We present ultraviolet and visual spectropolarimetry of the interactin g binary star beta Lyrae, obtained with the Wisconsin Ultraviolet Phot o-Polarimeter Experiment and the HPOL spectropolarimeter at Pine Bluff Observatory. Our observations span 3 years and cover the wavelength r ange from 1400 to 10500 Angstrom, with a resolution of 7.5-16 Angstrom . Detailed broad-and narrowband spectropolarimetric analysis allows us to begin to decompose the complex spectrum of beta Lyr: by examining the polarization behavior of a line or continuum, we can determine whi ch component scatters the light and, ultimately, from which component that light originates. After removing interstellar polarization from o ur data and rotating the results to the apparent intrinsic position an gle of the system, we find that the polarization of the hydrogen Balme r and vacuum ultraviolet ''UV bump'' emission lines, as well as that o f the near-UV continuum, remains mostly constant with phase and is ori ented at 90 degrees to the visible polarization, indicating that the s cattering plane of the light in these three spectral components is per pendicular to the scattering plane of the visible light. We propose th at the UV bump, Balmer emission, and near-UV continuum polarization is produced by electron scattering within a bipolar outflow in the beta Lyr system. The intrinsic visible polarization of beta Lyr shows eclip ses that associate it with material near the accretion disk. We find c onflicting evidence regarding both the origin of this visible light an d the scattering surface that polarizes it: continuum evidence points toward the secondary object as the illuminator and the accretion disk edge as the scatterer, while line analysis suggests that light from th e loser scatters off material between it and the disk. The presence of material away from the orbital plane may help resolve this contradict ion.